As Col. Connelly is flying his approach on the town where the Germans are, an American flag can be seen flying at what is presumed to be a post office. Also when the view switches to the side window view, several modern cars can be seen in the parking lots of the buildings. Furthermore, a large palm tree is visible in the "German" town (23 minute mark).
There were NO operational B-25s stationed in England with either the 8th or 9th Air Forces. The 25th Bomb Group (Reconnaisance) had some for weather and photo recon until replaced by Mosquito PR. IXs prior to D-Day. The B-26 Martin Marauder was however used by both the 8th and 9th AFs in England.
Major Stovall was never grounded in Season 2 due to poor eyesight. In Season 2's Storm at Twilight (1965), there are questions about his eyesight and he nearly grounds himself, but eventually returns to combat as Colonel Gallagher's co-pilot and brings the aircraft home when Gallagher is wounded, after which Gallagher tells Stovall, "Harvey, when this is all over, you can fly me home!"
The cockpit scenes of the "B-25" were actually filmed in the cockpit of a C-47 cargo aircraft which looks nothing like the cockpit of an actual B-25.